Method of sharpening surgical needles using a magnetic needle rack



Aug. 23, 1966 G. s BUCCINO 3,268,428

METHOD OF SHARPENING SURGICAL NEEDLES USING A MAGNETIC NEEDLE RACK Filed Jan. 5, 1962 I5. 5 fIE 4 Arrae/vn United States Patent 3,268,428 METHOD 0F SHARPENING SURGICAL NEEDLES USING A MAGNETIC NEEDLE RACK Gaetano Salvatore Buccino, Bethel, ConrL, assignor to American Cyanamid Company, New York, N.Y., a corporation of Maine Filed Jan. 3, 1962, Ser. No. 163,977 1 Claim. (Cl. 204-142) This invention relates to an apparatus and method for the anodic electrolytic sharpening of needles, particularly surgical needles by placing the needles on the face of a permanent magnet which serves both as physical support and electrical contact for the needle after which the rack-mounted needles are immersed in an etching solution and anodically etched.

Surgical needles need to be very sharp for preferred penetration. They may range from a shank diameter of about 0.008 inch to about 0.050 inch. They are curved and in the past have preferably been sharpened before bending to curvature. It is diflicult to sharpen a curved needle 'by mechanical abrasion. When the needles are sharpened before bending, the edges may be dulled during subsequent manufacturing operations.

To electrolytically etch edges on needles requires that the needles be supported mechanically and that an electact be made to the needle. A clip or clamp can be used but the contact surface is protected and the clip or clamp is of an electrically conducting metal and is subject to attacks by the etching solution.

With drilled-end needles, the needle may be supported on a point or wire, but such racking is quite. tedious.

It has now been found that the needles may be supported on the flat surface of a permanent magnet by magnetic attraction. Surgical needles usually are the drilledend, or flanged end type, either of which have a flat butt, which if placed in contact with the flat magnet surface, fixedly positions the needle and also serves as an electrical contact for the flow of the etching electric current.

Suitable magnets may be supported in a rack body. Electrical contact is made to the rack body and all rack surfaces which are immersed in the electrolyte are protected by a resist except the surfaces in contact with the needles.

It is convenient to grind the surface of the. magnets fiat. As at least part of the surface is exposed to the action of the electrolyte and accordingly sacrificed to the electrolyte. This surface of the magnet may become unevently etched, and hence require regrinding to maintain a flat surface. A single magnet may be ground many times before becoming so short as to require replacement. Many different configurations and contact surfaces may be used in conjunction with the present invention; but illustrative of preferred embodiments are those shown in the attached drawings:

FIGURE 1 is a single vertical rack having a plurality of magnets.

FIGURE 2 shows a cross bar rack with magnets in the cross bar.

FIGURE 3 shows the regrinding of the magnet face.

FIGURE 4 shows a plurality of needles on a single magnet face.

As shown in FIGURE 1, a rack body 11 has attached to the top thereof a contact hook 12. The contact hook should be of such shape as to fit over and make contact with a support bar to support the rack body and make electrical contact therewith when the rack is positioned in an electrolytic bath. In the main part of the rack body are inserted a number of magnets 15. Conveniently the magnets are permanent magnets of a conductive highly magnetic material such as Alnico or other highly 3,268,423 Patented August 23, 1966 magnetic materials, including magnetized steel. Other methods of attachment may .be used but a convenient method is for the magnets 15 to be cylindrical and fit in holes in the rack body 11 so that the magnets are both supported by and make electrical contact with the rack body.

The rack body itself is conveniently of copper because copper has a very high electrical conductivity.

The ends of the. magnets extend outward on both sides from the rack body. The main surfaces are coated with a resist 13. This resist may be a synthetic rubber cement, natural rubber, or an asphalt paint of the type conventionally used in electroplating baths to protect metal from the corrosive effect of the electrolyte. At least that portion of the rack body and magnets which is submerged in the electrolyte is coated. All of the surfaces may be coated except that portion of the contact hook which makes electrical contact with a source of electrical power and the flat faces 16 of the magnet.

The flat faces 16 of the magnet are exposed to the electrolyte when in use.

In use the surgical needles 17 are placed on their butts on the flat faces of the magnets. Either flanged or drilled end needles have a square cutoff at the rear. The needle butt 18 is at right angles to the needle and will support the needle in whatever position the needle is placed. As shown in FIGURE 1, it is convenient to have needles on opposed sides of opposite faces of each magnet.

A second configuration is shown in FIGURE 2 in which the rack body has cross bars 14 in which cross bars are the magnets. Two magnets are shown on each cross bar but a larger number may be used. With cross bars it is convenient to place a group of needles on each magnet face such as shown in FIGURE 4 where the needles cluster around the magnet like the petals of a flower.

Because the ends of the magnet are exposed, the anodic etching of the needles also causes an attack of the exposed flat face of the magnet and certain portions of the magnet are protected by the needle butts so the etching may be not completely uniform. With wear the face of the magnet may deviate sufficiently from flatness that the needles do not rack conveniently. When this occurs the faces of the magnets are again ground true, as shown in FIGURE 3, where a grinding wheel 19 again grinds the faces of the magnets smooth and true.

The faces of the magnets are the poles and the magnetic flux easily flows longitudinally of the needles and is curved around towards the opposed end of the magnet, roughly approximating the natural position of the lines of magnetic force.

In use, after the needles are placed on the flat faces of the magnets, the rack body is immersed in the electrolyte and the needles anodically etched until smooth, polished and sharp. Conveniently, the needles are swaged to approximate size before etching, and the etching both polishes and sharpens the needles.

Various types of electrolytes can be used for the polishing operation, including such materials as 300 parts by volume of phosphoric acid and 60 parts of water. Another suitable bath consists of 1500 volumes of phosphoric acid, volumes of water and 400 volumes of ethylene glycol.

Another good polishing bath consists of 69% ethylene glycol, 13% water, 11% free glycolic acid and 7% glycolic acid as the glycolide. Glycolic acid is readily dehydrated to the glycolide or polyglycolide by heating. The glycolic acid preparations may be used as such or mixed with 3 to 4 times their weight of phosphoric acid.

Other polishing solutions include such baths as are shown by United States Patents 2,607,724; 2,348,517; 2,386,078; 2,740,755; and 2,773,821.

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For preferred usages and the smoothest etching, the needles are placed symmetrically on the flat faces of the magnets in such a position as not to shadow each other or cause any needle to be markedly closer to the cathode than its neighboring needles. Thus the electrolytic effect is uniform over the needles.

What is claimed is:

A method of securing steel surgical needles, having a fiat butt at right angles to the needle, in an anodic etching bath and anodically etching the needles comprising: placing steel surgical needles having a fiat butt at right angles to the needle axis on the bare flat planar polar surface of an etchable permanent magnet, thereby mechanically supporting the needles at right angles to the magnet and making electrical contact with said needles, immersing the magnet-supported needles in an anodic polishing bath, passing an anodic current through the magnet and needles until the needles are both sharp and polished, removing the magnet and needles from said bath, rinsing the needles until electrolyte free, removing the needles from said magnet, during which etching of the needles, the needle contacting surfaces of the magnet are also etched, and periodically regrinding the contact surfaces of said magnet to a plane surface, whereby the surface continues to support subsequent batches of needles in ordered array and without tipping.

References Cited by the Examiner UNITED STATES PATENTS 1,005,870 10/1911 Packer 204 297 2,766,194 10/1956 Certa. 2,803,595 8/1957 Anzaldi. 3,038,475 6/1962 Orcutt 204 142 FOREIGN PATENTS 353,332 7/1931 Great Britain.

OTHER REFERENCES Belke Plating Rack Manual, June 18, 1947, p. 98.

JOHN H. MACK, Primary Examiner.

D. R. JORDAN, Assistant Examiner. 

